Quaternary ammonium salts are known to have the power to destroy numerous bacteria or viruses. Thus, the unexamined Japanese patent published under number 7-089907 in the name of Osaka Pharmaceutical Co. Ltd. indicates that didecyl dimethyl ammonium chloride is an antimicrobial agent having a disinfectant action, a strong bactericidal action with a broad antibiotic spectrum.
Therefore, said molecules are widely used in formulations intended for hygiene in the home, in hospital or other environments.
In a standard fashion quaternary ammonium salts, which are water-soluble, are used in antimicrobial applications in liquid form. In order to be effective, these solutions must be used at a certain concentration and, like quaternary ammonium salts, are not fixed to solid supports; after use, they remain in the treated aqueous phase or are removed and can therefore create long-term pollution.
The preparation of antimicrobial agents comprising solidified didecyl dimethyl ammonium chloride is difficult given the properties of this product. It has also been sought to fix quaternary ammonium salts to supports in order to be able to recover them more easily after use.
A subject of the abovementioned Japanese patent application is a powdery or pasty product comprising a high level of didecyl dimethyl ammonium chloride, obtained by mixing didecyl dimethyl ammonium chloride and an alkali metal phosphate, dried at 100-130° C. This patent describes a method of solidification in which all of the mixture containing the didecyl dimethyl ammonium chloride is solidified. It also describes a method for producing a solid formulation containing at least 40% didecyl dimethyl ammonium chloride.
The Japanese patent application published under number 2003-160412 in the name of Asahi Denka Kogyo KK describes an antibacterial biodegradable powder obtained by the impregnation of a powder preferably consisting of silica gel, zeolite or activated carbon with a quaternary ammonium salt comprising at least one ester group and comprising in particular 3 other C1 to C4 alkyl radicals. The quaternary ammonium salt taken into consideration in this patent application is an ester, the quaternary nitrogen atom comprising an ester substituent of formula [(C2-4 alkylene)-O]1-5—COalkyl or [(C2-4 alkylene)-O]1-5—CO-alkenyl. This application relates to the obtaining of heatresistant, sustained-release forms, comprising an antimicrobial agent other than a tetraalkyl ammonium salt and in particular other than didecyl dimethyl ammonium chloride.
The patent FR 2891545 in the name of La Brunière describes polyamide powders to which quaternary ammoniums are chemically fixed via a diisocyanate, using the —NH— groups of the polyamide chains. The field of application of this patent is limited to the polyamides and to the quaternary ammonium molecules possessing an —OH or —NH2 functional group for example, capable of reacting with an isocyanate.
The patent EP 0952168A of Toray Industries describes a method for obtaining a grafted copolymer formed by polymerization with grafting of structural units containing quaternary ammonium groups and the presence of a substituent consisting of halogen ions, sulphates, sodium hydroxides and carboxylic acids. This technique requires the utilization of a monomer comprising a halogen atom and is more generally limited to grafting onto thermoplastic polymers.
The problem that the invention proposes to solve is to have an insoluble powdery material containing a powder readily available commercially, which material attracts bacteria by physical routes by fixing them on both sides, and has antibacterial properties leading to the destruction of the bacteria. The invention also proposes to solve the problems encountered by wearers of masks comprising filters the antibacterial materials of which, used in their composition, are carried towards the respiratory tracts of the mask wearer and cause respiratory problems.
None of the known materials makes it possible to achieve this objective, namely to obtain such a powder by such a method nor, moreover, does it make it possible to obtain the surprising and unexpected results that the powder according to the invention makes it possible to obtain.